1. Field of the Invention
The present invention relates to an image processing apparatus, control method, and program for obtaining a monochrome output material from image data using a scanner.
2. Description of the Related Art
A conventional image processing apparatus includes both RGB color sensors and a BW monochrome sensor and switches between a color mode and a monochrome mode. A method is proposed for achieving quick monochrome reading and obtaining a high-quality color image (see Japanese Patent Laid-Open No. 2006-54903). According to this method, in the monochrome mode, a signal from the monochrome sensor is divisionally processed using not only an A/D converter for the monochrome sensor but also an A/D converter for the color sensors.
Japanese Patent Laid-Open No. 2006-54903 describes a color reading mode in which RGB color sensors read an original, and a monochrome reading mode in which a BW monochrome sensor reads an original. However, in Japanese Patent Laid-Open No. 2006-54903, the color reading mode and monochrome reading mode are not selectively used when outputting a monochrome image of an original.
When a color original is read in the monochrome reading mode in monochrome output, the reading speed is greatly increased when compared to when it is read in the color reading mode. However, the tone reproducibility of a specific color sometimes deteriorates greatly. This is because a filter corresponding to the BW monochrome sensor has a characteristic similar to that of a G filter (green filter) and information of part of the blue and red bands is lost. In contrast, when a color original is read in the color reading mode, the tone reproducibility is improved but the reading speed is low because the original is read using a plurality of sensors.